Question

If increasing 30 by y percentage results the same number as decreasing 40 by y percent then what is the value of y

Answer 1

The value of y is $\frac{100}{7}$.

Step-by-step explanation:

Increasing 30 by "y" percentage = $30\times \frac{(100 + y)}{100}$

Decreasing 40 by "y" percentage = $40\times \frac{(100-y)}{100}$

Increasing 30 by "y" percentage = Decreasing 40 by "y" percentage

=> $30\times \frac{(100 + y)}{100}$ = $40\times \frac{(100-y)}{100}$

=> 3 x (100 + y) = 4 x (100 - y)

=> 300 + 3y = 400 - 4y

=> 4y + 3y = 400 - 300

=> 7y = 100

=> y = $\frac{100}{7}$

Hence, the value of y is $\frac{100}{7}$.